Susceptibility is the quantification for the change in an extensive property when there is variation in the intensive property.
Magnetic susceptibility is the measure of the magnetic properties of a material in the field of electromagnetism. The magnetic susceptibility indicates whether there is attraction or repulsion of a material inside or outside the magnetic field. It has implications for the practical applications.
It is dimensionless proportionality constant which indicates the degree of magnetization of any material with response to the applied magnetic field. Magnetizability is the proportion between the magnetic moment and the magnetic flux density. Permeability is the parameter which expresses the total magnetization of the material and volume.
If the magnetic susceptibility is positive in nature, then the material is paramagnetic, or ferromagnetic, or ferromagnetic or anti-ferromagnetic in nature. In this reference, the presence of the material results in the strengthening of the magnetic field. Magnetic susceptibility is high in value when it comes to Ferro magnets.
If the magnetic susceptibility is negative in nature, then the material is diamagnetic in nature. This results in weakening of the magnetic field in presence of the material.
Magnetic susceptibility depends upon temperature with exceptions to most diamagnets, few paramagnets, alkali metals and alkaline earths. Diamagnetic materials are constant, and characterised by small negative susceptibilities, and they only get slightly affected by the change in temperature. Paramagnetic materials have small positive susceptibilities which are constant, which is inversely proportional to the value of the absolute temperature. Ferromagnetic materials do not have constant susceptibilities and the magnetization is not always proportional to the field strength applied.
MEASURES OF SUSCEPTIBILITY
1) Mass magnetic susceptibility
2) Molar magnetic susceptibility
EXPERIMENTAL METHOD TO DETERMINE SUSCEPTIBILITY
Volume magnetic susceptibility is measured the change of force felt upon the substance when magnetic field gradient is applied on it. Earlier, the measurements were made using the Gouy balance.
In Gouy balance, a sample substance is hung between the poles of an electromagnet. When the electromagnet is turned on, the change is weight occurs. That change in weight is proportional to the susceptibility.
Now, the measurement technique has changed and we use superconductive magnet. Evans balance is used to measure the force change on strong compact magnet with insertion of the sample.
APPLICATIONS OF MAGNETIC SUSCEPTIBILITY
- It provides insight into the structure of materials.
- It also provides an insight into the bonding and energy levels of the material.
- The records of magnetic susceptibility are often used for inter-core correlation as the changes in magnetic susceptibility correlates with the change in sedimentary provenance and also digenetic environment.